Each period in history sees the sky in a different way. The way a civilization perceives the sky is related to its travel capabilities. As man's knowledge of geography has increased, so has his understanding of the earth's place in the larger scheme.
Greek astronomer Ptolemy lived in the second century. He wrote a book called The Almagest. He had the earth at the center with the sun and planets going around it. This view stood for 1400 years.
In 1453, Copernicus in Poland got it right. He expounded a heliocentric doctrine. Modern science was born. Really, Copernicus revived a forgotten idea of the Greek Aristarchus. The Greeks had science. The Scientific Revolution grew out of the Renaissance which was a return to Greek ideas. The Middle Ages had been dominated by the Church, and the Bible frowned on science. It put revelation above observation. Galileo clashed with the Church when he taught the earth goes around the sun.
The road leading from superstition and false information was long. For centuries, man's concepts of reality were shaped by the Bible. Nowhere in the Bible does it state the earth is flat, but the implications are there, Satan taking Jesus to the mountaintop to show him the world's kingdoms and references to "four corners of the earth." Heaven was above. Hell was below. Even Shakespeare retarded the growth of science with ghosts, witches and fairies. No wonder, the people who first settled in America knew so little about the nature of the cosmos.
Things were changing. Europe was expanding, and the printing press spread new ideas. By the time of Columbus' voyages, most people knew the earth is round. It became irrefutable when Magellan sailed around it, a gruelling three-year voyage during which Magellan was killed.
Tycho Brahe was an observer. He found a supernova in Cassiopeia in 1572. As a theorist, he was lacking. He knew the planets circled the sun but thought both planets and sun circled the earth. He built an observatory near Hamlet's castle in Denmark.
It took Johannes Kepler, Tycho's assistant, to make sense of his work. Kepler's laws of planetary motion showed planetary orbits to be ellipses. The closer a planet is to the sun, the faster it moves.
William Herschel was the father of stellar astronomy. He built big telescopes and made the first model of the Milky Way. Erroneously, he placed our solar system at its center.
Isaac Newton and Albert Einstein were physicists who laid the groundwork on which modern astronomy is built. Newton introduced the concept of gravity, the tendency for two bodies to attract whether they are the earth and an apple or the earth and the moon. Einstein gave us relativity. Relativity says time is relative to speed, that the speed of light is the only absolute. While the most distant galaxies may be receding at 99% of the speed of light, they will never equal it. According to Einstein, gravity results from space being curved.
Newton was an alchemist. Einstein did not believe the universe was expanding. Even geniuses can be wrong! There is some question about the speed of light being absolute. Why does it have to be? If we travel faster than light, would we be in the dark when we reach our destination?
Astronomy is studied as a series of levels proceeding outward. Space has depth. There are motions within motions. Perspective rules. We explore the solar system. We reach for the stars. The Milky Way becomes one of countless galaxies. We question the origin and destiny of the universe. We search for extraterrestrial life.
ASTRONOMY
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